S e c t i o n 1 3 - P a g e 1 4 May 2013 T ypical Liner Plate Installations Liner Plates Only The most obvious advantages of this structur e ar e that maximum support per foot of tunnel is obtained with minimum weight of steel. Liner plates, pr operly gr outed or backflled as tunneling pr ogr esses, form a dependable structur e in either cohesive or non-cohesive gr ound. Liner plate structur es generally r equir e no additional support in tunnels up to 14' in diameter . Ribs Inside Liner Plates T o give extra support to a liner plate structur e in lar ge diameter or heavy load conditions, ribs can be added inside the ring. Liner plates then act as lagging and ar e normally lighter in gage. This additional support usually r equir es an incr ease in the diameter of the driven bor e to maintain the dimensions of the fnished inside diameter . This method is often used in shaft construction. Liner Plates Between Ribs This type of structur e is less common than ribs inside liner plates because it is har der to er ect. It does of fer a practical trade-of f under certain tunneling conditions. Thr ee basic ways sof installing plates in tunnels or shafts ar e illustrated her e; each has its advantage in a particular application or gr ound condition. www .dsiundergr ound.com